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Maintaining dynamic Equilibrium
The Importance of a Circulatory System
Introduction:
Circulatory systems range from systems that rely on simple chemical diffusion up to the complex
arrangement of arteries, veins and four-chambered heart of birds and mammals. Animal circulatory systems
perform a number of functions:
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they deliver oxygen and nutrients to cells
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they remove waste products from cells and tissues
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they distribute heat and hormones
By the end of this activity you should be able to:
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Describe the essential features of open and closed circulatory systems.
Contrast the structure and function of the heart in different groups of vertebrates.
Describe the differences between arteries, veins and capillaries, and what their roles are.
List the major components of blood and their function.
Understand the pulmonary and systemic circulation of blood in a human.
Describe the anatomy and function of the human heart.
Explain how the human heart beat is controlled by impulses, and how the heart beat relates to an
electrocardiograph trace.
Understand the causes and effects of cardiovascular disease.
Let’s begin by looking at animals that lack a distinct circulatory system.
Briefly describe circulation in amoeba, sponges and flatworms. Use your text page 242-243 and the animation #2 to
help with your answer.
Why will diffusion not do for more complex multi-cellular animals? Based on the hypothetical data from the animation,
how long would it take a molecule to diffuse through your body?
Where does one find interstitial fluid and what is its function?
Open and Closed Circulatory systems
Two basic types of circulatory systems have evolved in animals. Many invertebrates have an open circulatory system,
while vertebrates have a closed circulatory system. The later is often called a cardiovascular system because it
consists of a heart and a network of tube-like vessels.
Refer to your text and to the animation and explain the difference between closed and open systems of circulation.
Be sure to give examples of organisms that use each system.
The development of gill breathing in fish and lung breathing in land animals needed a more efficient circulatory system.
Vertebrate hearts have evolved from relatively simple structures (as in fish) to more complex organs such as those found in
mammals. Use the animation link #3 and Bio 11- 456-458
Distinguish between an atrium and a ventricle.
For each of the organisms above describe the number and arrangement of heart chambers. Where do you see the
development of the septum? What is the limitation of each of the above systems? Why does it work for the organisms
that display this type of circulation?
Fish
Amphibians
Reptiles
Define the following terms:
Systemic circuit
Gill circuit
Pulmocutaneous circuit
Pulmonary circuit
Blood Vessels Structure and Function (Bio11 250-254 and animation # 4)
In advanced circulatory systems there are three main
components: a fluid to move materials, a pump and a system
of vessels to carry the fluid. There are three main categories
of blood vessels: arteries, veins and capillaries. Study the
relationship of these vessels to each other in the diagram to
the right.
Arteries carry blood _______________________ the heart.
Veins carry blood ________________________ the heart.
Explain why the walls of the arteries need to be thick with a
lot of elastic tissue.
Relate your pulse to your arteries.
What is an aneurysm?
What is artherosclerosis?
Birds and Mammals
What are arterioles?
Compare vasoconstriction and vasodilatation.
Relate the terms above to blushing and the color draining from your face? What is the advantage to you of these
uncontrollable (autonomic) responses?
Your body circulates about 5 liters of blood. If all of the arterioles were open to the capillary beds how much blood would
your body require?
Contrast the structure of the veins and arteries for each of the following properties:
Thickness of muscle and elastic tissue:
Presence of valves:
With respect to their functional roles, give a reason for the difference you have
described above.
Blood oozes from a venous wound rather than spurting as it does from an arterial
wound. (Gross!!!) Account for the difference:
If the blood pressure is so low in veins how, then, does blood return to the heart from
the capillary beds?
Oh no!!!! You have varicose veins!!!! What are they and why do we get them?
In vertebrates, capillaries are very small vessels that connect arterial and venous circulation and allow efficient exchange of
nutrients between the blood and tissues.
What is the purpose of a capillary bed? Can you locate it on the diagram on the previous page?
What are the advantages and disadvantages of capillaries being composed of a single cell layer?
Components of Blood (Biology 11 244-246 and animation #4)
Plasma: composition and function?
Red Blood Cells (Erythrocytes) function?
White Blood Cells (Leukocytes) function?
Platelets function?
The Mammalian Heart (Biology 11 256-261 and animation #5) This link is also quite good!!
Refer to the handout “Mammalian Transport” Read the intro and the overview of the Human circulatory System.
Complete the diagram by filling in boxes a-f with the correct organ or structure they represent. Make sure that you take the
time to study the structures and their functions.
Refer to the handout “The Human Heart” and to the beautiful diagram of the heart on page 257 of your text.
Answer questions 1-7 on the handout.
Pretend you are a Red Blood Cell that has just dropped off its oxygen to brain tissue and is heading back to the heart. List
in order the vessels, blood chambers and organs that the blood must pass through if it will eventually find its way to the legs
and then back to the heart.
Although I will not make you responsible for this…..finish animation 5 by having a look at the way the heart beat is regulated.
Define Diastole:
Define Systole:
In preparation for Monday’s class…. Go to Lab Bench on my web page and go to the Circulatory Physiology section.
Work through Concepts 1-5